The ZSM-5 catalyst has received significant attention in recent years due to its significant properties such as strong acidity and high surface area. Crystal size of the catalyst has been recognized as an important factor in its performance. This review investigates the effects of the crystal size of ZSM-5 on its catalytic performance-selectivity; conversion; lifetime, product distribution; and coke formation during methanol to hydrocarbons (MTH), methanol to dimethyl ether, ethanol to gasoline (ETG), ethylene to gasoline (ETG), acetone to gasoline (ATG), acetone to olefin (ATO), naphtha cracking, and and n-dodecane cracking processes. This study demonstrates that the reduction of crystal size leads to higher levels of activity, conversion, and stability in these various processes.